Active energy ray-curable ink composition for inkjet printing

Abstract

To provide an active energy ray-curable ink composition for inkjet printing which is excellent in adhesion, flexibility, stretchability, alcohol resistance, and printing image quality.SOLUTION: The active energy ray-curable ink composition for inkjet printing contains a photopolymerizable compound. The photopolymerizable compound contains (A) a hydroxyl group-containing polyfunctional monomer, (B) a monomer and / or an oligomer having an amino group and / or an amide group, and (C) a monofunctional monomer other than the (B). The proportion of the hydroxyl group-containing polyfunctional monomer is 2 mass% or more and 20 mass% or less and the proportion of the monofunctional monomer is 50 mass% or more in the photopolymerizable compound.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to an actinic ray-curable ink composition for ink-jet printing. [Background technology]

[0002] 2. Description of the Related Art In the past, it has been proposed to incorporate a large amount of monofunctional monomers in actinic ray-curable inks for inkjet printing in order to improve adhesion to a substrate (for example, Patent Documents 1 to 3). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2007 / 055332 [Patent Document 2] International Publication No. 2013 / 027672 [Patent Document 3] JP 2014-70135 A Summary of the Invention [Problem to be solved by the invention]

[0004] Increasing the amount of monofunctional monomer improves adhesion and stretchability, but reduces resistance to solvents and inks, and for example, when printing using the single-pass method, the cured coating film is partially dissolved in the secondary color ink, making it difficult for dots to spread on the coating film and adversely affecting print quality. In order to achieve sufficient image quality, it is necessary to incorporate a large amount of polyfunctional monomer, but in that case, physical properties such as adhesion decrease, making it difficult to achieve both image quality and adhesion / stretchability.

[0005] An object of the present invention is to provide an actinic ray-curable ink composition for ink-jet printing that is excellent in adhesion, flexibility, stretchability, alcohol resistance, and print image quality. [Means for solving the problem]

[0006] That is, the present invention has the following configuration. [1] An active energy ray-curable ink composition for inkjet printing, comprising a photopolymerizable compound, the photopolymerizable compound comprising (A) a hydroxyl group-containing polyfunctional monomer, (B) a monomer and / or oligomer having an amino group and / or an amide group, and (C) a monofunctional monomer other than (B), wherein the proportion of the hydroxyl group-containing polyfunctional monomer in the photopolymerizable compound is from 2% by mass to 20% by mass, and the proportion of the monofunctional monomer is 50% by mass or more. [2] The active energy ray-curable ink composition for inkjet printing according to [1] above, wherein the proportion of the monomer and / or oligomer having an amino group and / or an amide group in the photopolymerizable compound is preferably 10% by mass or more and 40% by mass or less. [3] The active energy ray-curable ink composition for inkjet printing according to [1] or [2] above, further comprising a polyfunctional monomer other than (A) and (B), wherein the total ratio of the hydroxyl group-containing polyfunctional monomer and the polyfunctional monomer in the photopolymerizable compound is preferably 20 mass % or less. [4] The active energy ray-curable ink composition for inkjet printing according to any one of [1] to [3] above, wherein the monomer and / or oligomer having an amino group and / or an amide group preferably contains acryloylmorpholine and / or N-vinylcaprolactam. [5] The active energy ray-curable ink composition for inkjet printing according to [4] above, wherein the monomer and / or oligomer having an amino group and / or an amide group preferably contains an acrylated amine compound having two photopolymerizable functional groups and two amino groups in the molecule. [6] The active energy ray-curable ink composition for inkjet printing according to any one of [1] to [5] above, wherein the total proportion of photopolymerizable compounds having a glass transition temperature of 10° C. or lower contained in the photopolymerizable compounds is 20 mass % or more. [7] The actinic ray-curable ink composition for ink-jet printing according to any one of [1] to [6] above, which preferably contains a colorant. Effect of the Invention

[0007] The actinic ray-curable ink composition for ink jet printing of the present invention contains a specific photopolymerizable component, and as a result, the composition has excellent adhesion, flexibility, stretchability, alcohol resistance, and print image quality. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] The active energy ray-curable ink composition for ink-jet printing (hereinafter also referred to as ink composition) of the present invention will be described in detail below.

[0009] The active energy ray-curable ink composition for inkjet printing of the present invention contains a photopolymerizable compound, and the photopolymerizable compound contains (A) a hydroxyl group-containing polyfunctional monomer, (B) a monomer and / or oligomer having an amino group and / or an amide group, and (C) a monofunctional monomer other than (B), and in the photopolymerizable compound, the proportion of the hydroxyl group-containing polyfunctional monomer is 2% by mass or more and 20% by mass or less, and the proportion of the monofunctional monomer is 50% by mass or more.

[0010] <(A) Hydroxyl group-containing polyfunctional monomer> The hydroxyl group-containing polyfunctional monomer may have two or more photopolymerizable functional groups and a hydroxyl group in the molecule, and examples thereof include 2-hydroxy-3-methacrylpropyl acrylate, glycerin diacrylate, isocyanuric acid EO-modified diacrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, tripentaerythritol hexa(meth)acrylate, and tripentaerythritol penta(meth)acrylate. The hydroxyl group-containing polyfunctional monomer may be used alone or in combination of two or more kinds. From the viewpoint of adhesion, the hydroxyl group-containing polyfunctional monomer preferably has two photopolymerizable functional groups and a hydroxyl group in the molecule.

[0011] The ratio of the hydroxyl-containing polyfunctional monomer in the photopolymerizable compound is 2% by mass or more and 20% by mass or less. If the ratio of the hydroxyl-containing polyfunctional monomer in the photopolymerizable compound is less than 2% by mass, the alcohol resistance and image quality (dot diameter) decrease, and if it is more than 20% by mass, the adhesion, flexibility, and stretchability decrease. It is more preferable that the ratio of the hydroxyl-containing polyfunctional monomer in the photopolymerizable compound is 5% by mass or more and 12% by mass or less.

[0012] <(B) Monomer and / or Oligomer Having Amino Group and / or Amido Group> Examples of the monomer and / or oligomer having an amino group and / or an amide group include various (meth)acrylamide monomers such as acrylamide and acryloylmorpholine, vinylamide monomers such as N-vinylpyrrolidone, N-vinylformamide, N-vinylacetamide, N-vinylcaprolactam, N-vinylcarbazole, and vinylmethyloxazolidinone, and acrylated amine compounds such as trade names "CN371", "CN373", "CN386", "CN501", "CN550", and "CN551" (all manufactured by Sartomer Corporation). Among these, it is preferable to use a monomer having an amino group and / or an amide group, and it is more preferable to use acryloylmorpholine and / or N-vinylcaprolactam, and it is even more preferable to use an acrylated amine compound having two photopolymerizable functional groups and two amino groups in the molecule in combination with acryloylmorpholine and / or N-vinylcaprolactam. The above-mentioned monomers and / or oligomers having an amino group and / or an amide group may be used alone or in combination of two or more kinds.

[0013] The content of the monomer and / or oligomer having an amino group and / or an amide group can be determined arbitrarily. In the photopolymerizable compound, the ratio of the monomer and / or oligomer having an amino group and / or an amide group is preferably 10% by mass or more and 40% by mass or less, more preferably 15% by mass or more and 30% by mass or less, from the viewpoint of curability. If the ratio of the monomer and / or oligomer having an amino group and / or an amide group in the photopolymerizable compound is less than 10% by mass, the curability and tackiness may be reduced.

[0014] <(C) Monofunctional Monomer> The monofunctional monomer other than (B) (hereinafter also referred to as monofunctional monomer) may be any one that is used in known active energy ray-curable ink compositions for inkjet printing, and examples of such monofunctional monomers include butyl (meth)acrylate, isobutyl (meth)acrylate, tertiary butyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, decyl (meth)acrylate, isomyristyl (meth)acrylate, stearyl (meth)acrylate, and the like. acrylate, isostearyl (meth)acrylate, isobornyl (meth)acrylate, lauryl (meth)acrylate, cyclic trimethylolpropane formal (meth)acrylate, cyclohexyl (meth)acrylate, butylcyclohexyl acrylate, trimethylcyclohexyl acrylate, adamantyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate acrylates, styrene, benzyl (meth)acrylate acrylate, 2-phenoxyethyl (meth)acrylate and its ethylene oxide modified product, ethyl carbitol (meth)acrylate, 2-methoxyethyl acrylate, polyethylene glycol (meth)acrylate, isoamyl (meth)acrylate, hydroxymethyl (meth)acrylate, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, hydroxyphenoxypropyl (meth)acrylate, 2-ethylhexyl-diglycol (meth)acrylate, 2-acryloyloxyethyl hexahydrophthalic acid, butoxyethyl acrylate, ethoxydiethylene glycol (meth)acrylate, ethyl carbitol acrylate, methoxydiethylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, methoxypropylene glycol (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, (2-methyl-2-ethyl-1,Examples of the monofunctional monomer include (3-dioxolan-4-yl)methyl (meth)acrylate, (3-ethyloxetan-3-yl)methyl methacrylate, phenol ethylene glycol modified acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 2-acryloyloxyethyl succinate, 2-acryloyloxyethyl phthalate, 2-acryloyloxyethyl-2-hydroxyethyl-phthalate, lactone modified flexible acrylate, t-butylcyclohexyl (meth)acrylate, 3,3,5-trimethylcyclohexyl acrylate, vinyloxyethoxyethyl (meth)acrylate, and the like. The monofunctional monomers may be used alone or in combination of two or more.

[0015] The proportion of the monofunctional monomer in the photopolymerizable compound is 50% by mass or more. From the viewpoint of flexibility and stretchability, the proportion of the monofunctional monomer in the photopolymerizable compound is preferably 50% by mass or more and 90% by mass or less, and more preferably 60% by mass or more and 85% by mass or less.

[0016] <Polyfunctional Monomer Other than (A) and (B)> Examples of polyfunctional monomers other than (A) and (B) (hereinafter also referred to as polyfunctional monomers) include known polyfunctional monomers having two or more ethylenically unsaturated bonds, such as the following polyfunctional (meth)acrylate compounds and vinyl ether group-containing (meth)acrylate compounds. The polyfunctional monomers may be used alone or in combination of two or more kinds.

[0017] Examples of polyfunctional (meth)acrylate compounds include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, pentyl glycol di(meth)acrylate, Neopentyl glycol di(meth)acrylate, hydroxypivalyl hydroxypivalate di(meth)acrylate, hydroxypivalyl hydroxypivalate dicaprolactonate di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,2-hexanediol di(meth)acrylate, 1,5-hexanediol di(meth)acrylate, 2,5-hexanediol di(meth)acrylate, 1,7-heptanediol di(meth)acrylate, 1,8-octanediol di(meth)acrylate, 1,2-octanediol di(meth)acrylate, Nonanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, 1,2-decanediol di(meth)acrylate, 1,12-dodecanediol di(meth)acrylate, 1,2-dodecanediol di(meth)acrylate, 1,14-tetradecanediol di(meth)acrylate, 1,2-tetradecanediol di(meth)acrylate, 1,16-hexadecanediol di(meth)acrylate, 1,2-hexadecanediol di(meth)acrylate, 2-methyl ethyl-2,4-pentanediol di(meth)acrylate, 3-methyl-1,5-pentanediol di(meth)acrylate, 2-methyl-2-propyl-1,3-propanediol di(meth)acrylate, 2,4-dimethyl-2,4-pentanediol di(meth)acrylate, 2,2-diethyl-1,3-propanediol di(meth)acrylate, 2,2,4-trimethyl-1,3-pentanediol di(meth)acrylate, dimethylol octane di(meth)acrylate, 2-ethyl-1,3-hexanediol di(meth)acrylate,2,5-Dimethyl-2,5-hexanediol di(meth)acrylate, 2-Methyl-1,8-octanediol di(meth)acrylate, 2-Butyl-2-ethyl-1,3-propanediol di(meth)acrylate, 2,4-Diethyl-1,5-pentanediol di(meth)acrylate, Tricyclodecanedimethylol di(meth)acrylate, Tricyclodecanedimethylol dicaprolactonate di(meth)acrylate, Cyclohexanedimethanol di(meth)acrylate, Dicyclopentanyl di(meth)acrylate, Bis(meth)acrylate, Bisphenol A tetraethylene oxide adduct di(meth)acrylate, bisphenol F tetraethylene oxide adduct di(meth)acrylate, bisphenol S tetraethylene oxide adduct di(meth)acrylate, hydrogenated bisphenol A tetraethylene oxide adduct di(meth)acrylate, hydrogenated bisphenol F tetraethylene oxide adduct di(meth)acrylate, hydrogenated bisphenol A di(meth)acrylate, hydrogenated bisphenol F di(meth)acrylate, bisphenol A tetraethylene oxide Bifunctional monomers such as di(meth)acrylates of polyhydric alcohols such as dicaprolactonate di(meth)acrylate, bisphenol F tetraethylene oxide adduct dicaprolactonate di(meth)acrylate, glycerin, pentaerythritol, diglycerin, ditrimethylolpropane, and dipentaerythritol, glycerin tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolpropane tricaprolactonate tri(meth)acrylate, trimethylolethane ... trifunctional monomers such as trimethylolpropane tri(meth)acrylate, trimethylolhexane tri(meth)acrylate, trimethyloloctane tri(meth)acrylate, etc.; and their 3EO (ethylene oxide) modified products, 6EO modified products, and 9EO modified products (3EO modified trimethylolpropane tri(meth)acrylate, 3EO modified trimethylolethane tri(meth)acrylate, 3EO modified trimethylolhexane tri(meth)acrylate, etc.), trimethylolpropane tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate,Examples of monomers having 4 or more functional groups include pentaerythritol tetracaprolactonate tetra(meth)acrylate, diglycerin tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, ditrimethylolpropane tetracaprolactonate tetra(meth)acrylate, ditrimethylolethane tetra(meth)acrylate, ditrimethylolbutane tetra(meth)acrylate, ditrimethylolhexane tetra(meth)acrylate, ditrimethyloloctane tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, tripentaerythritol octa(meth)acrylate, and tripentaerythritol polyalkylene oxide hepta(meth)acrylate. Among these, preferred examples include trimethylolpropane triacrylate (TMPTA; trifunctional), ditrimethylolpropane tetraacrylate (DITMPTA; tetrafunctional), dipentaerythritol hexaacrylate (DPHA; hexafunctional), and hexanediol diacrylate (HDDA; bifunctional).

[0018] Examples of the vinyl ether group-containing (meth)acrylate compound include 2-vinyloxyethyl (meth)acrylate, 3-vinyloxypropyl (meth)acrylate, 1-methyl-2-vinyloxyethyl (meth)acrylate, 2-vinyloxypropyl (meth)acrylate, 4-vinyloxybutyl (meth)acrylate, 1-methyl-3-vinyloxypropyl (meth)acrylate, 1-vinyloxymethylpropyl (meth)acrylate, and 2-methyl-3-vinyloxypropyl (meth)acrylate. Pyr, (meth)acrylate-3-methyl-3-vinyloxypropyl, (meth)acrylate-1,1-dimethyl-2-vinyloxyethyl, (meth)acrylate-3-vinyloxybutyl, (meth)acrylate-1-methyl-2-vinyloxypropyl, (meth)acrylate-2-vinyloxybutyl, (meth)acrylate-4-vinyloxycyclohexyl, (meth)acrylate-5-vinyloxypentyl, (meth)acrylate-6-vinyloxyhexyl, (meth)acrylate-4-vinyloxymethylcyclohexyl xylmethyl, (meth)acrylate-3-vinyloxymethylcyclohexylmethyl, (meth)acrylate-2-vinyloxymethylcyclohexylmethyl, (meth)acrylate-p-vinyloxymethylphenylmethyl, (meth)acrylate-m-vinyloxymethylphenylmethyl, (meth)acrylate-o-vinyloxymethylphenylmethyl, (meth)acrylate-2-(vinyloxyisopropoxy)ethyl, (meth)acrylate-2-(vinyloxyethoxy)propyl, (meth)acrylate-2-( (vinyloxyethoxy)isopropyl, (meth)acrylate-2-(vinyloxyisopropoxy)propyl, (meth)acrylate-2-(vinyloxyisopropoxy)isopropyl, (meth)acrylate-2-(vinyloxyethoxyethoxy)ethyl, (meth)acrylate-2-(vinyloxyethoxyisopropoxy)ethyl, (meth)acrylate-2-(vinyloxyisopropoxyethoxy)ethyl, (meth)acrylate-2-(vinyloxyisopropoxyisopropoxy)ethyl, (meth)acrylate-2-(vinyloxyisopropoxyisopropoxy)ethyl.

[0019] When the polyfunctional monomer is used, the ratio of the polyfunctional monomer in the photopolymerizable compound is preferably 5% by mass or less, more preferably 3% by mass or less. When the polyfunctional monomer is used, the total ratio of the hydroxyl group-containing polyfunctional monomer (A) and the polyfunctional monomer in the photopolymerizable compound is preferably 2% by mass or more and 20% by mass or less.

[0020] In the ink composition, the total ratio of the photopolymerizable compounds having a glass transition temperature of 10° C. or less contained in the photopolymerizable compound is preferably 20% by mass or more and 60% by mass or less, more preferably 25% by mass or more and 50% by mass or less, from the viewpoint of flexibility and stretchability. Examples of the photopolymerizable compound having a glass transition temperature of 10° C. or less include the above-mentioned components, and examples of the monofunctional monomer having a glass transition temperature of 10° C. or less include methyl acrylate, ethyl acrylate, n-butyl acrylate, n-hexyl methacrylate, 2-ethylhexyl (meth)acrylate, iso-nonyl acrylate, tetrahydrofurfuryl (meth)acrylate, isooctyl (meth)acrylate, isoamyl acrylate, isomyristyl acrylate, lauryl acrylate, benzyl acrylate, phenoxyethyl acrylate, and ethyl carbitol acrylate. Examples of polyfunctional monomers and / or polyfunctional oligomers having a glass transition temperature of 10° C. or lower include polyethylene glycol (400) diacrylate, polyethylene glycol (600) diacrylate, alkoxylated hexanediol diacrylate, ethoxylated (30) bisphenol A diacrylate, alkoxylated neopentyl glycol diacrylate, ethoxylated (3) trimethylolpropane triacrylate, ethoxylated (6) trimethylolpropane triacrylate, ethoxylated (9) trimethylolpropane triacrylate, propoxylated (3) trimethylolpropane triacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, polyethylene glycol (600) dimethacrylate, ethoxylated (10) bisphenol A dimethacrylate, 1,12-dodecanediol dimethacrylate, urethane acrylate oligomer, and polyester acrylic oligomer.

[0021] <Photopolymerization initiator> The ink composition may contain a photopolymerization initiator. When an electron beam is used as the active energy ray, the ink composition may or may not contain a photopolymerization initiator. The photopolymerization initiator may be used alone or in combination of two or more kinds.

[0022] Examples of the photopolymerization initiator include acylphosphine oxide polymers such as bis-2,6-dimethoxybenzoyl-2,4,4-trimethylpentylphosphine oxide, 2,4,6-trimethylbenzyl-diphenylphosphine oxide (TPO), bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (Omnirad819 or SB-PI719), and ethoxy(2,4,6-trimethylbenzoyl)phenylphosphine oxide (TPOL). Polymerization initiators: 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]-phenyl}-2-methyl-propan-1-one (Omnirad 127), 2-hydroxy-4'-hydroxyethoxy-2-methylpropiophenone (Omnirad 2959), 1-hydroxycyclohexyl phenyl ketone (Omnirad 184), oligo{2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone} (ESACURE ONE), 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, bis[4-(2-hydroxy-2-methylpropanoyl)phenyl]ether (KIP160) and other α-hydroxyketone polymerization initiators;Benzophenone compounds (4,4'-diethylaminobenzophenone, etc.), 2-methyl-1-(4-methylthio)phenyl-2-morpholinopropan-1-one, 4'-(methylthio)-α-morpholino-α-methylpropiophenone, thiophenyl compounds (4-benzoyl-4'-methyldiphenyl sulfide), thioxanthone compounds (2,4-diethylthioxanthone, 1-chloro-4-propoxythioxanthone, isopropylthioxanthone), 2,2-dimethyl-2-hydroxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2-benzyl-2-dimethylamino-1-(morpholinophenyl)-butan-1-one, 4-benzoyl-4'-methyldiphenyl sulfide, ethyl Michler's ketone, polymer type initiators (Omnipol TP, Omnipol BP), 1-[4-(4-benzoylphenylsulfanyl)phenyl]-2-methyl-2-(4-methylphenylsulfonyl)propan-1-one (ESACURE1001M);

[0023] The content of the photopolymerization initiator is not particularly limited. For example, when ultraviolet light (UV) or ultraviolet light (light-emitting diode (LED)) is used as a light source, the content of the photopolymerization initiator in the ink composition is preferably 3% by mass or more, and more preferably 4% by mass or more. The content of the photopolymerization initiator in the ink composition is preferably 25% by mass or less, and more preferably 15% by mass or less. When the content of the photopolymerization initiator is within the above range, the ink composition can have sufficient curability, internal curability, and low cost.

[0024] <Sensitizer> In order to promote curing by ultraviolet light using a light-emitting diode (LED) as a light source, the ink composition may further contain a photosensitizer (compound) that has light absorption properties in the wavelength range of 400 nm or more, mainly ultraviolet light, and exhibits a sensitizing function for the curing reaction by light in that range of wavelengths, together with the polymerization initiator. Note that the above phrase "exhibits a sensitizing function by light with a wavelength of 400 nm or more" refers to having a light absorption property in the wavelength range of 400 nm or more. By using such a sensitizer, the ink composition of the present invention can promote LED curing.

[0025] Examples of the sensitizer include anthracene-based sensitizers such as 9,10-dibutoxyanthracene, 9,10-diethoxyanthracene, 9,10-dipropoxyanthracene, and 9,10-bis(2-ethylhexyloxy)anthracene; and thioxanthone-based sensitizers such as 4-isopropylthioxanthone, with thioxanthone-based sensitizers being preferred. Representative examples of commercially available products include anthracene-based sensitizers under the trade names "DBA" and "DEA" (all manufactured by Kawasaki Chemical Industries, Ltd.), and thioxanthone-based sensitizers under the trade names "DETX", "ITX", and "CPTX" (all manufactured by Lambson), and "Omnipol TX" (manufactured by IGM). The sensitizers may be used alone or in combination of two or more kinds.

[0026] The content of the sensitizer in the ink composition is preferably 0 to 8% by mass. If the content exceeds 8% by mass, no improvement in effect is observed, and it is undesirable because it is an excessive addition.

[0027] In addition, when a thioxanthone-based sensitizer is used as the sensitizer, it tends to discolor the active energy ray curable inkjet printing ink composition to yellow, resulting in a yellowish hue compared to the color (original hue) based on the pigment, etc., so it is preferable to appropriately determine the content of the thioxanthone-based sensitizer for each color. Specifically, in the white ink composition and the clear ink composition, which are easily affected by changes in color, it is preferable not to include a thioxanthone-based compound as a sensitizer. In addition, in the magenta ink composition and the cyan ink composition, changes in hue become a problem, so it is preferable to use them within a range where no problems occur in hue. In addition, in the black ink composition and the yellow ink composition, since discoloration does not affect the hue and the active energy ray polymerizability is poorer than other hues, it is preferable to use a thioxanthone-based compound in combination as a sensitizer.

[0028] <Coloring agent> The ink composition may contain a colorant of each hue to obtain an ink composition of each color. As such a colorant, any pigment or dye that has been conventionally used in normal photocurable ink jet printing ink compositions may be used without any particular limitation, but in consideration of light resistance, pigments such as organic pigments or inorganic pigments are preferred.

[0029] Examples of the organic pigments include dye lake pigments, azo-based, benzimidazolone-based, phthalocyanine-based, quinacridone-based, anthraquinone-based, dioxazine-based, indigo-based, thioindigo-based, perylene-based, perinone-based, diketopyrrolopyrrole-based, isoindolinone-based, nitro-based, nitroso-based, flavanthrone-based, quinophthalone-based, pyranthrone-based, indanthrone-based pigments, etc. Examples of the inorganic pigments include carbon black, titanium oxide, red iron oxide, graphite, iron black, chromium oxide green, aluminum hydroxide, etc.

[0030] Specific examples of pigments for each representative hue include the following:

[0031] Examples of yellow pigments for use in the yellow ink composition include CI Pigment Yellow 1, 2, 3, 12, 13, 14, 16, 17, 42, 73, 74, 75, 81, 83, 87, 93, 95, 97, 98, 108, 109, 114, 120, 128, 129, 138, 139, 150, 151, 155, 166, 180, 184, 185, and 213, and preferably CI Pigment Yellow 150, 155, 180, and 213.

[0032] Examples of magenta pigments for use in the magenta ink composition include CI Pigment Red 5, 7, 12, 22, 38, 48:1, 48:2, 48:4, 49:1, 53:1, 57, 57:1, 63:1, 101, 102, 112, 122, 123, 144, 146, 149, 168, 177, 178, 179, 180, 184, 185, 190, 202, 209, 224, 242, 254, 255, 270, and CI Pigment Violet 19, and preferably CI Pigment Red 122, 202, and Pigment Violet 19.

[0033] Examples of cyan pigments for use in the cyan ink composition include CI Pigment Blue 1, 2, 3, 15, 15:1, 15:2, 15:3, 15:4, 15:6, 16, 18, 22, 27, 29, 60, and the like, and preferably CI Pigment Blue 15:4, and the like.

[0034] An example of a black pigment for use in the black ink composition is carbon black (CI Pigment Black 7).

[0035] Examples of white pigments for use in the white ink composition include titanium oxide and aluminum oxide, and preferably titanium oxide that has been surface-treated with various materials such as alumina and silica.

[0036] The content of the pigment in the ink composition is preferably 1 to 20% by mass based on the total amount of the ink composition. If the content of the pigment is less than 1% by mass, the image quality of the resulting printed matter tends to decrease. On the other hand, if the content of the pigment is more than 20% by mass, the viscosity characteristics of the ink composition tend to be adversely affected.

[0037] <Pigment dispersant> The ink composition may contain a pigment dispersant as necessary. The pigment dispersant is used to improve the dispersibility of the pigment and the storage stability of the ink composition, and any conventionally used pigment dispersant may be used without particular limitation. Among them, it is preferable to use a polymer dispersant. Examples of the pigment dispersant include carbodiimide-based dispersants, polyester amine-based dispersants, fatty acid amine-based dispersants, modified polyacrylate-based dispersants, modified polyurethane-based dispersants, multi-chain polymer nonionic dispersants, and polymer ionic surfactants. The pigment dispersants may be used alone or in combination of two or more kinds.

[0038] The pigment dispersant is preferably contained in an amount of 1 to 200 parts by mass when the total amount of the pigments used is taken as 100 parts by mass. If the content of the pigment dispersant is less than 1 part by mass, the pigment dispersibility and storage stability of the ink composition may decrease. On the other hand, it may be contained in an amount of more than 200 parts by mass, but there may be no difference in effect. The lower limit of the content of the pigment dispersant is more preferably 5 parts by mass, and the upper limit is more preferably 60 parts by mass.

[0039] <Other ingredients> The ink composition may contain various additives to exhibit various functionalities as necessary. Specifically, the ink composition may contain various additives such as surfactants, organic solvents, polymerization inhibitors, light stabilizers, surface treatment agents, ultraviolet absorbers, antioxidants, defoamers, antifungal agents, rust inhibitors, thickeners, moisturizers, and pH adjusters. In addition, a resin that functions as a vehicle but is not curable may or may not be blended.

[0040] <Surfactant (Leveling Agent)> The surfactant (leveling agent) is not particularly limited, and examples thereof include nonionic surfactants, cationic surfactants, anionic surfactants, betaine surfactants, etc. More specifically, examples of the surfactant include silicone surfactants such as polyether-modified silicone oil, polyester-modified polydimethylsiloxane, and polyester-modified methylalkylpolysiloxane, fluorine-based surfactants, and acetylene-based surfactants.

[0041] Examples of silicone surfactants include BYK-307, BYK-315N, BYK-331, BYK-333, BYK-347, BYK-348, BYK-349, BYK-345, BYK-377, BYK-378, and BYK-3455 (manufactured by BYK-Chemie).

[0042] Examples of fluorine-based surfactants include F-410, F-444, F-553 (manufactured by DIC Corporation), FS-65, FS-34, FS-35, FS-31, and FS-30 (manufactured by DuPont).

[0043] Examples of acetylene surfactants include Dynol 607, Dynol 609, Olfin E1004, Olfin E1010, Olfin E1020, Olfin PD-001, Olfin PD-002W, Olfin PD-004, Olfin PD-005, Olfin EXP.4001, Olfin EXP.4200, Olfin EXP.4123, Olfin EXP.4300 (manufactured by Nissin Chemical Industry Co., Ltd.), Surfynol 104E, Surfynol 104H, Surfynol 104A, Surfynol 104BC, Surfynol 104DPM, Surfynol 104PA, Surfynol 104PG-50, Surfynol 420, Surfynol 440, and Surfynol 465 (manufactured by EVONIK).

[0044] When the surfactant is blended, the content of the surfactant is not particularly limited. For example, the content of the surfactant in the ink composition is preferably 0.005% by mass or more, more preferably 0.01% by mass or more, from the viewpoint of improving the ejection stability of the ink composition from the inkjet head. The content of the surfactant in the ink composition is preferably 1.5% by mass or less, more preferably 1% by mass or less.

[0045] <Organic solvent> The organic solvent is not particularly limited, and examples thereof include ester-based organic solvents, ether-based organic solvents, ether ester-based organic solvents, ketone-based organic solvents, aromatic hydrocarbon solvents, nitrogen-containing organic solvents, etc. When an organic solvent is blended, the content of the organic solvent is not particularly limited, and, for example, is preferably 5% by mass or less, and more preferably 2% by mass or less, in the ink composition.

[0046] <Polymerization inhibitor> The polymerization inhibitor is not particularly limited, and examples thereof include hindered amines such as N-CH3 type, NH type, and N-OR type, phenol-based, amine-based, sulfur-based, and phosphorus-based polymerization inhibitors.

[0047] <Ultraviolet absorbing agent> Examples of the ultraviolet absorber include benzophenone-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, salicylate-based ultraviolet absorbers, hydroxyphenyltriazine-based ultraviolet absorbers, cyanoacrylate-based ultraviolet absorbers, and nickel complex salt-based ultraviolet absorbers.

[0048] <Antioxidants> Examples of the antioxidant include phenol-based antioxidants, amine-based antioxidants, sulfur-based antioxidants, and phosphorus-based antioxidants.

[0049] <Antifoaming agent> Examples of the defoaming agent include silicone-based defoaming agents and Pluronic (registered trademark)-based defoaming agents.

[0050] <Preparation of Ink Composition> The method for preparing the ink composition is not particularly limited, and the ink composition can be prepared by adding all of the above-mentioned materials and mixing them in a bead mill, a three-roll mill, etc. It is also possible to prepare a concentrated base ink in advance by mixing a pigment, a pigment dispersant, and a photopolymerizable compound, and then add additives such as a photopolymerizable compound, a photopolymerization initiator, and, if necessary, a surfactant to the concentrated base ink so as to obtain a desired ink composition.

[0051] The substrate on which the ink composition is printed is preferably, for example, a substrate made of flooring, acrylic, vinyl chloride, polyethylene terephthalate, polycarbonate, or the like, but any substrate on which a conventional photocurable inkjet printing ink composition can be printed (paper, plastic film, capsule, gel, metal foil, glass, cloth, or the like) can be used without any problem.

[0052] Specifically, the method of printing and curing the ink composition includes a method of ejecting the ink composition onto a substrate using an inkjet head for low viscosity, and then exposing the coating film of the ink composition of the present invention that has landed on the substrate to light and curing it. For example, ejection onto a substrate (printing of an image) can be performed by supplying the ink composition to a printer head for low viscosity inkjet recording printer, and ejecting the ink composition from the printer head so that the coating film on the substrate has a thickness of, for example, 1 to 60 μm. Furthermore, exposure to light and curing (curing of an image) can be performed by irradiating the coating film of the ink composition applied to the substrate as an image with light.

[0053] As the printer for inkjet recording that prints the ink composition, a printer for inkjet recording equipped with an inkjet head can be used. When a continuous type printer for inkjet recording is used, a conductivity imparting agent is further added to the ink composition to adjust the electrical conductivity.

[0054] Examples of light sources for curing the coating film include ultraviolet light (UV), ultraviolet light (light-emitting diode (LED)), electron beams, visible light, etc., and from an environmental standpoint, light-emitting diodes (LED) that generate ultraviolet light with an emission peak wavelength in the range of 350 to 420 nm and electron beams are preferred. Ultraviolet light using a light-emitting diode (LED) as a light source refers to "light irradiated from a light-emitting diode that generates ultraviolet light with an emission peak wavelength in the range of 350 to 420 nm." EXAMPLES

[0055] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples in any way.

[0056] The raw materials used are shown below. <(A) Hydroxyl group-containing polyfunctional monomer> 2-Hydroxy-3-methacrylpropyl acrylate: manufactured by Shin-Nakamura Chemical Co., Ltd. Glycerin diacrylate: Toagosei Co., Ltd. Isocyanuric acid ED modified diacrylate: Toagosei Co., Ltd. <(B) Monomer and / or Oligomer Having Amino Group and / or Amido Group> Acroylmorpholine: ACMO, manufactured by KJ Chemicals Vinylcaprolactam: VCAP, manufactured by ISP Japan Amine-modified oligomer: an acrylated amine compound having two photopolymerizable functional groups and two amino groups in the molecule, CN371NS: manufactured by Sartomer Corporation <(C) Monofunctional Monomer Other Than (B)> Benzyl acrylate: Miramer M1182HP, manufactured by MIWON, glass transition temperature 6°C Phenoxyethyl acrylate: Miramer M140, manufactured by MIWON, glass transition temperature 5°C Ethyl carbitol acrylate: Viscoat #190, manufactured by Osaka Organic Chemical Industry Co., Ltd., glass transition temperature -67°C Isobornyl acrylate: IBXA, manufactured by Osaka Organic Chemical Industry Co., Ltd., glass transition temperature 88°C <Polyfunctional Monomer Other than (A) and (B)> 1,6-Hexanediol diacrylate: SR238NS, manufactured by Sartomer 3-Methyl-1,5-pentanediol diacrylate: SR341, manufactured by Sartomer <Photopolymerization initiator> TPO: 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, manufactured by Lambson <Sensitizer> DETX: 2,4-diethylthioxanthone, manufactured by Lambson <Polymerization inhibitor> MEHQ: Hydroquinone monomethyl ether <Surfactant (Leveling Agent)> BYK-315N: Silicone surface conditioner, 100% solids, manufactured by BYK-Chemie <Coloring agent> PB15:4 PR122 PY150 PBk7 <Pigment dispersant> Dispersant 1: SS32000, manufactured by Lubrizol Japan Dispersant 2: PB821: Ajinomoto Fine-Techno Co., Ltd. <Base material> Acrylic plate (Mitsubishi Chemical Acrylite L·S) PVC plate (Takiron C.I. T938) PVC80 (manufactured by Lintec)

[0057] <Production of active energy ray-curable ink composition for inkjet printing> A mixture of raw materials other than the photopolymerization initiator, sensitizer, polymerization inhibitor, and leveling agent, blended to the composition (mass%) shown in Table 1, was dispersed using an Eiger mill (zirconia beads with a diameter of 0.5 mm were used as media) to obtain a concentrated base. Using the obtained concentrated base, the photopolymerization initiator, sensitizer, polymerization inhibitor, and leveling agent were blended to the composition (mass%) shown in Table 1, to obtain active energy ray-curable inkjet printing ink compositions of Examples 1 to 12 and Comparative Examples 1 to 6.

[0058] <Evaluation of printed matter> The active energy ray-curable ink jet printing ink compositions of Examples 1 to 12 and Comparative Examples 1 to 6 were used to evaluate the substrate adhesion, flexibility, stretchability, alcohol resistance, and image quality (dot diameter) of the ink compositions according to the following evaluation methods and evaluation criteria. The results are shown in Table 1. The printing conditions were as follows: printing on the substrate with a single-pass printer (head: Ricoh M5320), followed by curing by LED irradiation (irradiation energy 500 mJ).

[0059] <Adhesion to substrate> The cured coating film of each ink composition printed on an acrylic plate (Acrylite L·S manufactured by Mitsubishi Chemical Corporation) was cross-cut with a utility knife, and cellophane tape (product name: Cellotape (registered trademark), manufactured by Nichiban Co., Ltd.) was applied to the cut area and then peeled off to evaluate the degree of peeling of the cured coating film according to the following criteria. [Evaluation Criteria] 5: Less than 5% of the coating peeled off 4: Paint peeling is between 5% and 15% 3: Paint peeling is 15% or more but less than 35% 2: Paint peeling is 35% or more but less than 65% 1: More than 65% of the coating has peeled off. The results were visually evaluated on a relative scale of 5 to 1. The pass criteria was 5 or 4.

[0060] <Flexibility> The cured coating film of each ink composition printed on a PVC plate (T938 manufactured by Takiron CI) was visually observed for cracks when bent at 180° C. and evaluated according to the following criteria. 5: No cracks in the coating 4: Cracks occur in less than 10% of the bent area. 3: Cracks occur in 10% to 30% of the entire bent area. 2: Cracks occur in 30% to less than 50% of the bent area. 1: Cracks occur in more than 50% of the bent area. The results were visually evaluated on a relative scale of 5 to 1. The pass criteria was 5 or 4.

[0061] <Stretchability> The cured coating of each ink composition printed on a PVC plate (T938 manufactured by Takiron CI) was cut to a size of 2 cm x 5 cm, and the coating was visually inspected for cracks when stretched to 100% and evaluated according to the following criteria. [Evaluation Criteria] 5: No cracking of the coating even at 100% elongation. 4: Cracks occur when elongated between 75% and 100% 3: Cracks occur at elongations between 50% and 75%. 2: Cracks occur at elongations between 25% and 50%. 1: Cracks occur when stretched less than 25%. The results were visually evaluated on a relative scale of 5 to 1. The pass criteria was 5 or 4.

[0062] <Alcohol resistance> The cured coating of each ink composition printed on a PVC plate (T938 manufactured by Takiron CI) was rubbed 10 times with a cotton swab containing 50% ethanol, and the degree to which the coating was removed was visually observed and evaluated according to the following criteria. [Evaluation Criteria] 5: The coating did not come off even after rubbing 10 times with a cotton swab. 4: After rubbing with a cotton swab 8 or 9 times, the coating begins to come off. 3: After rubbing with a cotton swab 6 or 7 times, the coating begins to come off. 2: After rubbing with a cotton swab four or five times, the coating begins to come off. 1: The coating begins to come off after rubbing with a cotton swab two or three times. The results were visually evaluated on a relative scale of 5 to 1. The pass criteria was 5 or 4.

[0063] <Image quality (dot diameter)> The same ink was printed at a low printing rate on the coating of each ink composition printed on PVC80 (manufactured by Lintec Corporation), and the UV-LED light was measured with a Phoseon Technology UV-LED lamp at a distance of 2 cm from the ink coating surface, with a UV integrated light amount of 180 mJ / cm. 2 The surface of this coating was observed with a microscope manufactured by Keyence Corporation, and the diameter of the printed dots was measured. [Evaluation Criteria] 5: Dot diameter is 75μm or more 4: Dot diameter is 70μm or more and less than 75μm 3: Dot diameter is 65μm or more and less than 70μm 2: Dot diameter is 60μm or more and less than 65μm 1: Dot diameter is less than 60 μm The pass criteria was 5 or 4.

[0064] [Table 1]

Claims

1. An active energy ray-curable ink composition for ink-jet printing, comprising a photopolymerizable compound, The photopolymerizable compound contains (A) a hydroxyl group-containing polyfunctional monomer, (B) a monomer and / or oligomer having an amino group and / or an amide group, and (C) a monofunctional monomer other than (B), the photopolymerizable compound contains a hydroxyl group-containing polyfunctional monomer in an amount of 2% by mass or more and 20% by mass or less, and a monofunctional monomer in an amount of 50% by mass or more.

2. 2. The active energy ray-curable ink composition for inkjet printing according to claim 1, wherein a ratio of the monomer and / or oligomer having an amino group and / or an amide group in the photopolymerizable compound is 10% by mass or more and 40% by mass or less.

3. Contains a polyfunctional monomer other than (A) and (B), The active energy ray-curable ink composition for inkjet printing according to claim 1 , wherein a total ratio of the hydroxyl group-containing polyfunctional monomer and the polyfunctional monomer in the photopolymerizable compound is 20 mass % or less.

4. 3. The active energy ray-curable ink composition for ink-jet printing according to claim 1, wherein the monomer and / or oligomer having an amino group and / or an amide group contains acryloylmorpholine and / or N-vinylcaprolactam.

5. 5. The active energy ray-curable ink composition for inkjet printing according to claim 4, wherein the monomer and / or oligomer having an amino group and / or an amide group contains an acrylated amine compound having two photopolymerizable functional groups and two amino groups in the molecule.

6. 3. The active energy ray-curable ink composition for inkjet printing according to claim 1, wherein a total ratio of photopolymerizable compounds having a glass transition temperature of 10° C. or lower contained in the photopolymerizable compound is 20 mass % or higher.

7. The actinic ray-curable ink composition for ink-jet printing according to claim 1 or 2, further comprising a colorant.

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